Wash potatoes well and dice
into large cubes, approximately 1- by 1-inch. Place potatoes in saucepan; add
cold water to just cover. Bring to simmer, and cook until just tender.

While potatoes are cooking,
prepare vinaigrette: Add vinegars, dry mustard and honey to bowl of food
processor. Pulse to combine. With processor running, slowly add oils to combine
into emulsified dressing. After adding oils, process in herbs and salt and
pepper to taste. Warm vinaigrette in small saucepan.

When potatoes are cooked, drain
well and put in a mixing bowl. Add haricot verts and diced red pepper. While
still warm, pour vinaigrette over potato mixture and toss all ingredients
gently to combine. Check seasoning. Serve salad warm or at room temperature.